Understanding Climate Change
The following information is aimed at providing people with a good level of understanding on climate change and why action needs to be taken now.
This has been taken, with kind permission, from climatechange.gov.uk - a UK government backed initiative led by Defra in partnership with the Energy Saving Trust, the Carbon Trust, the Department of Trade and Industry, the Environment Agency, the UK Climate Impacts Programme and the Department for Transport. For more information please visit www.climatechallenge.gov.uk.
What is the 'climate'?
The term 'climate' normally describes the average weather we get over a long period of time. When our climate changes, the weather we experience locally day to day can also change.
Over the millions of years of the earth's existence, the climate has changed many times. However, when we use the term 'climate change' now, it is to describe shifts in temperature over approximately the last 100 years and the next 100 years or so.
What causes climate change?
There will always be some degree of uncertainty in understanding a system as complex as the world's climate. However, there is now strong evidence and almost unanimous agreement that significant global warming is occurring. It is also likely that most of the recent warming can be attributed to human activities.
Natural causes
Some changes to the earth's climate are caused by the effects on each other of the sun, land, oceans and atmosphere. These often occur over very long periods of time.
Human causes
Human activity has changed the concentration of greenhouse gases in the atmosphere in two important ways. First, we have cut down forests to develop land for agriculture. Trees absorb carbon dioxide so, with fewer trees, more carbon dioxide builds up in the atmosphere. Also, the agriculture that replaces the forests can often be a source of emissions.
Second, by burning fossil fuels like coal, oil and gas for energy, we release greenhouse gases. Currently, burning fossil fuels emits about 6.5 billion tonnes of carbon dioxide into the atmosphere each year. Since before the industrial revolution, which began in the 18th century, concentrations of greenhouse gases have increased by 30 per cent.
What effects will climate change have?
Even if we stop burning fossil fuels and cutting down forests today, the world's climate will still warm in years to come. There is a time lag between when the emissions occur and when we begin to feel their effects, so we have yet to experience the impact of the greenhouse gas emissions from the last 30-40 years.
Scientists have identified some of the likely effects of this warming.
Rainfall
Some regions will experience more extreme rainfall while others will experience drought.
Sea level
The sea level could rise by more than 40 centimetres by the end of the century. There are two reasons for this. First, as the water in the oceans warms, it expands. Second, ice from the polar caps and from glaciers is melting into the sea. Rising sea levels will completely swamp some small, low-lying island states and put millions of people in low-lying areas at risk.
Water
There will be less water available for irrigation and drinking because there will be less rain, and salt from rising sea levels will contaminate ground water in coastal areas. Droughts are likely to be more frequent. Three billion more people could suffer increased water shortages by 2080. Northern Africa, the Middle East and the Indian subcontinent will be the worst affected.
Harvest
As temperatures increase and rainfall patterns change, cereal crop yields are expected to drop significantly in Africa, the Middle East and India.
Disease
As temperatures increase, the areas that harbour diseases such as malaria, West Nile disease, dengue fever and river blindness will shift. It is predicted that 290 million additional people could be exposed to malaria by the 2080s, with China and Central Asia seeing the biggest increase in risk.
Rainforests
Higher temperatures and reduced rainfall could mean the loss of large areas of Brazilian and southern African rainforest - on top of the forest that we are cutting down to clear land for agriculture. These forests currently act as a 'sink' by absorbing large amounts of carbon dioxide which would otherwise be released into the atmosphere.
What can we do about climate change?
We can't stop the effects of the greenhouse gas emissions that have already taken place. But we can influence the future.
The majority of scientists agree that to avoid radical changes of temperature in the future, action is needed now.
Many believe that emissions of greenhouse gases, which are continuing to rise, must begin to decline over the next 10-20 years to avoid extreme changes to our climate.
Carbon dioxide is the main greenhouse gas that causes climate change. Every tonne emitted into the atmosphere commits the world to more warming. But every tonne we avoid emitting helps reduce the risk.
The good news is there are lots of ways we can tackle climate change. Many of them will bring other benefits, such as new jobs, improved local environments and economic growth.
But the first step is to increase people's awareness and understanding of what's happening. Despite research showing that in the UK most people have heard of 'climate change' and 'global warming', the understanding of what causes climate change remains low.
By communicating climate change successfully, we'll be able to make sure that there is widespread support for the goal that together this generation will tackle climate change.
Key climate facts
Big changes in the atmosphere
In just 200 years, the amount of carbon dioxide in the atmosphere - the major gas that causes climate change - has increased by 30 per cent. Concentrations of greenhouse gases are now higher than at any point in the past 800,000 years.
Global temperature warming
Over the past century, average near-surface global temperatures have risen by 0.7°C.
Hot decade
The ten warmest years on record have all been since 1990. Six of the ten warmest years on record in the UK were between 1995 and 2004.
In Europe, the August 2003 heatwave was probably the hottest for at least 500 years.
During August 2003, the hottest temperature ever recorded in the UK was taken in Brogdale in Kent. It was 38.5°C.
Between 4 and 13 August 2003, over 2,000 people in the UK died as a result of the heat.
Big increase in flood victims
The autumn and winter floods in 2000 in the UK were the worst for 270 years in some areas. Flooding on farmland cost the farming industry nearly £500 million.
For more information, please visit www.carbonchallenge.gov.uk